public inbox for gcc-cvs-wwwdocs@sourceware.org
help / color / mirror / Atom feed
* gcc-wwwdocs branch master updated. df48cfe754f3ec94c83955c29133baa9580bc1df
@ 2020-10-06 15:04 David Malcolm
0 siblings, 0 replies; only message in thread
From: David Malcolm @ 2020-10-06 15:04 UTC (permalink / raw)
To: gcc-cvs-wwwdocs
This is an automated email from the git hooks/post-receive script. It was
generated because a ref change was pushed to the repository containing
the project "gcc-wwwdocs".
The branch, master has been updated
via df48cfe754f3ec94c83955c29133baa9580bc1df (commit)
from 693cc9122512b580926acacf2b7516b0a23b770a (commit)
Those revisions listed above that are new to this repository have
not appeared on any other notification email; so we list those
revisions in full, below.
- Log -----------------------------------------------------------------
commit df48cfe754f3ec94c83955c29133baa9580bc1df
Author: David Malcolm <dmalcolm@redhat.com>
Date: Tue Oct 6 11:02:22 2020 -0400
gcc-11/changes: Add notes about column number changes
diff --git a/htdocs/gcc-11/changes.html b/htdocs/gcc-11/changes.html
index 64655120..e2a32e51 100644
--- a/htdocs/gcc-11/changes.html
+++ b/htdocs/gcc-11/changes.html
@@ -72,6 +72,45 @@ a work-in-progress.</p>
control if function entries and exits should be instrumented.</li>
</ul>
</li>
+ <li>
+ <p>
+ In previous releases of GCC, the "column numbers" emitted in diagnostics
+ were actually a count of bytes from the start of the source line. This
+ could be problematic, both because of:
+ </p>
+ <ul>
+ <li>multibyte characters (requiring more than one byte to encode), and</li>
+ <li>multicolumn characters (requiring more than one column to display in a monospace font)</li>
+ </ul>
+ <p>
+ For example, the character π ("GREEK SMALL LETTER PI (U+03C0)")
+ occupies one column, and its UTF-8 encoding requires two bytes; the
+ character 🙂 ("SLIGHTLY SMILING FACE (U+1F642)") occupies two
+ columns, and its UTF-8 encoding requires four bytes.
+ </p>
+ <p>
+ In GCC 11 the column numbers default to being column numbers, respecting
+ multi-column characters. The old behavior can be restored using a new
+ option
+ <a href="https://gcc.gnu.org/onlinedocs/gcc/Diagnostic-Message-Formatting-Options.html#index-fdiagnostics-column-unit">-fdiagnostics-column-unit=byte</a>.
+ There is also a new option
+ <a href="https://gcc.gnu.org/onlinedocs/gcc/Diagnostic-Message-Formatting-Options.html#index-fdiagnostics-column-origin">-fdiagnostics-column-origin=</a>,
+ allowing the pre-existing default of the left-hand column being column
+ 1 to be overridden if desired (e.g. for 0-based columns). The output
+ of
+ <a href="https://gcc.gnu.org/onlinedocs/gcc/Diagnostic-Message-Formatting-Options.html#index-fdiagnostics-format">-fdiagnostics-format=json</a>
+ has been extended to supply both byte counts and column numbers for all source locations.
+ </p>
+ <p>
+ Additionally, in previous releases of GCC, tab characters in the source
+ would be emitted verbatim when quoting source code, but be prefixed
+ with whitespace or line number information, leading to misalignments
+ in the resulting output when compared with the actual source. Tab
+ characters are now printed as an appropriate number of spaces, using the
+ <a href="https://gcc.gnu.org/onlinedocs/gcc/Preprocessor-Options.html#index-ftabstop">-ftabstop</a>
+ option (which defaults to 8 spaces per tab stop).
+ </p>
+ </li>
</ul>
<!-- .................................................................. -->
-----------------------------------------------------------------------
Summary of changes:
htdocs/gcc-11/changes.html | 39 +++++++++++++++++++++++++++++++++++++++
1 file changed, 39 insertions(+)
hooks/post-receive
--
gcc-wwwdocs
^ permalink raw reply [flat|nested] only message in thread
only message in thread, other threads:[~2020-10-06 15:04 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-10-06 15:04 gcc-wwwdocs branch master updated. df48cfe754f3ec94c83955c29133baa9580bc1df David Malcolm
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).